Method

Preheat oven to 200c.
Line a small baking tray with baking parchment. Pour the caster sugar onto the baking tray and heat for 7 minutes in the oven. Heating the sugar creates a glossy and stable mixture.
Meanwhile, slowly whisk the egg whites in a mixer, allowing small stabilising bubbles to form, then increase the speed until the egg whites form stiff peaks.
Remove the sugar from the oven and reduce the temperature to 100c. Leaving the door open can speed this up.
With the mixer on full speed, slowly spoon the hot sugar into the beaten egg whites, making sure the mixture comes back comes back to stiff peaks after each addition of sugar. Once all the sugar is added, continue to whisk on full speed until the mixture is smooth, stiff and glossy. Continue to whisk for 5 minutes to ensure the sugar is fully combined. The mixture shouldn’t feel gritty.
Spoon the meringue mixture into a disposable piping bag and cut the tip off, so the whole is about the size of a 50 pence coin. To pipe out a kiss, keep the bag tight, straight and directly above the baking tray. Squeeze from a 2cm height and release before pulling up to form the lovely peaks. Using a teaspoon, make an indent in the kiss, for the lemon curd.
Bake the meringue kisses for 35 to 45 minutes or until the meringue bases should come off the parchment paper.
While the meringues bake, being making the lemon curd.
Mix together the eggs and lemon juice in a saucepan. Slowly bring to a gentle boil, stirring continuously. When it comes to a boil, remove from the heat and whisk in the butter gradually until fully incorporated
Ensure the meringues are properly cooled before decorating with lemon curd.
Carefully fill the indent in the meringue with lemon curd, arrange on a platter and serve.